DESCRIPTION (Applicant's abstract): The goal of this research will be to understand the role of two subcortical brain structures, the basal ganglia and the cerebellum, in learning action sequences. Relative to cortical structures, the functional role of these structures in learning and producing sequenced action and how they interact with other brain areas are poorly understood. My research seeks to investigate hypotheses inspired by cognitive theories of sequence learning and neurological research. Using a behavioral paradigm called the serial reaction time (SRT) paradigm, sequence learning performance in Parkinson's disease patients, cerebellar patients, and normal control subjects will be contrasted. Specifically, hypotheses will be tested relating to the learning of response-related versus incidental information, the sensitivity of the system to spatial versus nonspatial stimulus dimensions and the ability to integrate temporal information into action sequences. Such issues are not only central to the theoretical analysis of cognitive and brain processes in sequence learning but are also crucial for understanding learning and coordination deficits in Parkinson's and cerebellar patients.